1. Field of Invention
The invention relates to a navigation system and a program and a storage medium for use in such a navigation system.
2. Description of Related Art
A navigation system searches for a route that gives the lowest sum of search costs assigned to respective road links along the route to the destination, and provides navigation guidance to a destination along the determined route. In some cases, an unsuitable route is selected, via such simple searching, because there are many types of vehicles that vary in length, width, height, and weight, and thus all types of vehicles cannot necessarily drive along the route selected. Japanese Unexamined Patent Application Publication No. 8-278157, incorporated herein by reference in its entirety, discloses a navigation system capable of acquiring vehicle information necessary in extracting roads on which a vehicle can drive, extracting roads on which the vehicle can drive based on the road information, and searching for a route to a destination using those extracted roads.
However, in the conventional navigation system, the search cost employed in searching for a route to a destination is determined mainly by the length of the road. As such, there is a possibility that a road can be selected that has a low search cost but that is unsuitable for driving. For example, a mountain road can be selected rather than a road that is much better in terms of drivability, such as a bypass or a newly surfaced road. It may be possible to avoid selecting roads unsuitable for driving when searching for a route, if data indicating such unsuitable roads is prepared. However, this method requires a greater amount of data stored in a storage means.